I’m going to show you how it is that we
look at how well someone can hear with their hearing aids.
What I have showing here is a figure, lower pitch sounds are shown to the left and then
higher pitched sounds are to the right. Volume is shown by going up on the graph so
louder sounds are higher on the figure. Someone with normal hearing falls, roughly,
where this dash line is. They can hear anything that is plotted above that dash line.
Then I have this little hatched area that is shown and that’s for someone who is talking
in a normal voice. Now, I have someone with a hearing loss shown
with this blue line. For that person, they can hear anything that’s plotted above that
blue line. They can hear these low-pitched sounds here
but nothing above that and that’s a problem. So, for this child, we want to take this hatched
area and move it up so they can hear it. After we’ve determined how sound goes into
that child’s ear, we take this hearing aid and attach it to this coupler.
What happens here is, this coupler has a microphone attached to it, and so it measures how loud
the sound is after it goes through the hearing aid.
I put the hearing aid down here and we’ve got speakers in here and the speakers play
the speech sound that I’m going to show to you.
We shut this box and then we play the speech. “A carrot is long reddish, yellow”
Now we’re playing the speech and we’re measuring how loud it is as it goes into that
child’s hearing aid. What we want to do is just basically turn
the volume of the hearing aid up so they can hear it.
Once we’ve done that, then we get a plot that looks like this, where we’ve taken
the white hatched area, through the hearing aid making speech louder now, as loud as what’s
shown in this purple hatched area. That’s how we can determine that the hearing
aid is set appropriately for that person’s hearing loss.